1. Field of the Invention
This invention relates to a projection image display device and a method of switching an image displayed on the device to a proper direction, and more particularly to a separate type projection image display device and a method of switching an image displayed on the device to a proper direction.
2. Prior Art
In general, conventional separate projection image display devices are classified into a front type device and a rear type device. Each of the front type and the rear type devices is further classified into a hanging front type one, an on-floor rear type one, a hanging rear type one, and an on-floor front type one. In any case, the separate type projection image display apparatus utilizes a cathode ray tube (CRT) projector or a liquid crystal projector. The CRT projector has a CRT from which RGB color lights are radiated and then focused by a lens to project RGB color images on a screen.
The liquid crystal projector has a liquid crystal panel to which light is radiated from a backward light source to be focused by a lens. Thus, an image is projected on a screen through the liquid crystal panel. On projecting a color image, RGB polarizing light components must be transmitted through a respective liquid crystal panel to form RGB images. These RGB images are focused by a lens and combined together on a screen.
Herein, it is to be noted that an image is not always displayed on a screen as a normal image but may be displayed upside down or inside out when each projection image display device is wrongly set. In other words, each projection image display device must be set or installed in place in consideration of the type of each projection image display unit so as to project and display such a normal image. Otherwise, an inverted image is displayed on the screen and may be inverted in a vertical direction and/or a horizontal direction.
In order to prevent an inverted image from being displayed, an operator should consider or recognize each type of the projection image display devices so as to normally display an image.
Consequently, the conventional separate type projection image display device is disadvantageous in that each type of the projection image display devices should be recognized by the operator and is installed or set in place in a situation determined at each type of the projection image display devices. Further, it is often difficult for an operator to be accustomed to every one of the projection image display devices. This brings about difficulty in handling the device.